Protein disulfide isomerase, or PDI, is an enzyme in the endoplasmic reticulum (ER) in eukaryotes and the periplasm of bacteria that catalyzes the formation and breakage of disulfide bonds between cysteine residues within proteins as they fold. This allows proteins to quickly find the correct arrangement of disulfide bonds in their fully folded state, and therefore the enzyme acts to catalyze protein folding.
Thioredoxin reductases are enzymes that reduce thioredoxin (Trx). Two classes of thioredoxin reductase have been identified: one class in bacteria and some eukaryotes and one in animals. In bacteria TrxR also catalyzes the reduction of glutaredoxin like proteins known as NrdH. Both classes are flavoproteins which function as homodimers. Each monomer contains a FAD prosthetic group, a NADPH binding domain, and an active site containing a redox-active disulfide bond.
Thioredoxin is a class of small redox proteins known to be present in all organisms. It plays a role in many important biological processes, including redox signaling. In humans, thioredoxins are encoded by TXN and TXN2 genes. Loss-of-function mutation of either of the two human thioredoxin genes is lethal at the four-cell stage of the developing embryo. Although not entirely understood, thioredoxin is linked to medicine through their response to reactive oxygen species (ROS). In plants, thioredoxins regulate a spectrum of critical functions, ranging from photosynthesis to growth, flowering and the development and germination of seeds. Thioredoxins play a role in cell-to-cell communication.
Glutathione reductase (GR) also known as glutathione-disulfide reductase (GSR) is an enzyme that in humans is encoded by the GSR gene. Glutathione reductase catalyzes the reduction of glutathione disulfide (GSSG) to the sulfhydryl form glutathione (GSH), which is a critical molecule in resisting oxidative stress and maintaining the reducing environment of the cell. Glutathione reductase functions as dimeric disulfide oxidoreductase and utilizes an FAD prosthetic group and NADPH to reduce one molar equivalent of GSSG to two molar equivalents of GSH:
Glutaredoxins are small redox enzymes of approximately one hundred amino-acid residues that use glutathione as a cofactor. In humans this oxidation repair enzyme is also known to participate in many cellular functions, including redox signaling and regulation of glucose metabolism. Glutaredoxins are oxidized by substrates, and reduced non-enzymatically by glutathione. In contrast to thioredoxins, which are reduced by thioredoxin reductase, no oxidoreductase exists that specifically reduces glutaredoxins. Instead, glutaredoxins are reduced by the oxidation of glutathione. Reduced glutathione is then regenerated by glutathione reductase. Together these components compose the glutathione system.
In enzymology, a malate dehydrogenase (quinone) (EC 1.1.5.4), formerly malate dehydrogenase (acceptor) (EC 1.1.99.16), is an enzyme that catalyzes the chemical reaction
Adenylyl-sulfate reductase (thioredoxin) is an enzyme that catalyzes the chemical reaction
In enzymology, a CoA-glutathione reductase (EC 1.8.1.10) is an enzyme that catalyzes the chemical reaction
In enzymology, a leghemoglobin reductase (EC 1.6.2.6) is an enzyme that catalyzes the chemical reaction
In enzymology, a L-methionine (R)-S-oxide reductase (EC 1.8.4.14) is an enzyme that catalyzes the chemical reaction
In enzymology, a L-methionine (S)-S-oxide reductase (EC 1.8.4.13) is an enzyme that catalyzes the chemical reaction
In enzymology, a nitrite reductase (NO-forming) (EC 1.7.2.1) is an enzyme that catalyzes the chemical reaction
Peptide methionine sulfoxide reductase (Msr) is a family of enzymes that in humans is encoded by the MSRA gene.
Methionine-R-sulfoxide reductase B2, mitochondrial is an enzyme that in humans is encoded by the MSRB2 gene. The MRSB2 enzyme catalyzes the reduction of methionine sulfoxide to methionine.
Methionine-R-sulfoxide reductase B1 is an enzyme that in humans is encoded by the SEPX1 gene.
Methionine sulfoxide is the organic compound with the formula CH3S(O)CH2CH2CH(NH2)CO2H. It is an amino acid that occurs naturally although it is formed post-translationally.
Methionine-S-oxide reductase (EC 1.8.4.5, methyl sulfoxide reductase I and II, acetylmethionine sulfoxide reductase, methionine sulfoxide reductase, L-methionine:oxidized-thioredoxin S-oxidoreductase) is an enzyme with systematic name L-methionine:thioredoxin-disulfide S-oxidoreductase. This enzyme catalyses the following chemical reaction
Peptide-methionine (S)-S-oxide reductase (EC 1.8.4.11, MsrA, methionine sulphoxide reductase A, methionine S-oxide reductase (S-form oxidizing), methionine sulfoxide reductase A, peptide methionine sulfoxide reductase, formerly protein-methionine-S-oxide reductase) is an enzyme with systematic name peptide-L-methionine:thioredoxin-disulfide S-oxidoreductase (L-methionine (S)-S-oxide-forming). This enzyme catalyses the following chemical reaction
Oxytocinase is a type of enzyme that metabolizes the endogenous neuropeptide, oxytocin. The most well-characterized oxytocinase is leucyl/cystinyl aminopeptidase, which is also an enkephalinase. Other oxytocinases are also known. During pregnancy, oxytocinase plays a role in balancing concentration of oxytocin by degrading the oxytocin produced by the fetus, as production of oxytocin increases with growth of fetus. One study found that concentration level of oxytocinase increased progressively with gestational age until labor, which indicates that pregnancy development can be statistically evaluated by comparing oxytocinase levels.
Dr. Herbert Weissbach NAS NAI AAM is an American biochemist/molecular biologist.
